The present invention relates to photographic cameras for taking three dimensional photographs utilizing a lenticular screen.
A number of methods and apparatus have been devised and proposed for taking and viewing three dimensional photographic pictures. One prior art method and apparatus has two cameras photograph the left and right images of an object on film. The exposed film is developed and is then viewed through a device which allows the user to view the left image with the left eye and the right image with the right eye. Disadvantages with such an arrangement are that two cameras are required for taking the photograph and further, the three dimensional image cannot be viewed with the naked eye because some type of viewer, reflective plates or colored filters are required to avoid reversal of the left and right images.
Methods and apparatus have also been proposed for exposing film through a lenticular screen having very small diameter, semicircular and parallel lenticular elements. The exposed film is then viewed through a similar lenticular screen by the naked eye. Such methods and apparatus sequentially expose film through the lenticular screen.
One method and apparatus using a lenticular screen involves a camera which is positioned at a number of different angles about the object being photographed, and for each position exposing film through the lenticular screen while moving the lenticular screen.
Another method and apparatus using a lenticular screen eliminates the need for moving the camera and includes the combination of a lenticular screen positioned in contact with unexposed film, an objective for focussing an image of a scene to be photographed on the lenticular screen, and a shutter which is movable across the path for light rays from the objective for sequentially exposing the film. With the latter method and apparatus it has been proposed to move at least two of the elements including the objective lens, the lenticular screen, the shutter curtain and the film, during the exposure cycle. However, it has been found to be very difficult to control and obtain sharp three dimensional viewing images using such method and apparatus. As a result these methods have generally resulted in low quality three dimensional photographs and the method and apparatus have not met with any substantial degree of success.
One of the last mentioned method and apparatus involved a camera in which there is movement of the film and the shutter curtain relative to the lenticular screen during the exposure cycle. Relative movement between the film and lenticular screen is generally required by some precise amount. If the precise amount of relative movement is not achieved, the three dimensional quality of the photograph will be poor or the photographic image cannot be seen at all. Where the film is moved it is difficult to control the precise amount of movement of the film and it is difficult to maintain uniform contact between the film and the lenticular screen. In the camera where the film is moved the shutter curtain and film are moved in opposite directions and the film is moved a distance substantially equal to the width of two of the lenticular elements. This results in double exposures underneath the lenticular elements, further contributing to poor quality in the three dimensional photograph. Additionally, the resulting photograph contains reversed images under each lenticular element requiring that the images be reversed using a reversing process before the images can be viewed.
The reversing process creates serious problems which make it unsatisfactory and undesirable. Specifically, the exposed film obtained from the exposure cycle of the aforementioned camera is developed into a transparency. A reversing machine positions, in parallel layered relation, a lenticular screen adjacent to the transparency which is adjacent to a new unexposed film. The reversing machine moves the lenticular screen, the transparency, and the new unexposed film while exposing the new unexposed film to an exposure light through the lenticular screen and the transparency. A lenticular screen must be selected which has the same diameter lenticular elements as in the camera and the distance of movement must be selected to correspond to the movement of the lenticular screen in the camera. However, the angle of deflection of the objective lens system varies from camera to camera and as a result a different amount of movement is required in the reversing process for each different objective lens system and hence camera. As a result it becomes necessary to design a different reversing machine, or at least select the amount of movement during reversing, for each different camera. Neither of the aforementioned is practical.
Japanese patent application No. 1971-20693 (Official Gazette No. 1972-37637), filed by the present inventor, discloses a camera for taking three dimensional photographs utilizing a lenticular screen, having small diameter lenticular elements, closely placed adjacent the unexposed film in which the objective lens focusses an image from the scene to be photographed onto the lenticulated side of the lenticular screen. A shutter screen bearing a shutter aperture is moved across the optical path between the objective lens and the lenticular screen, while the lenticular screen moves a distance equal to one pitch of the lenticular screen. Significantly the shutter and lenticular screen are moved in the same direction relative to the film and as a result an unreversed three dimensional image is formed on the film. Thus the film may be developed into a print and placed behind a lenticular screen for direct viewing without additional image reversing steps. However, it has been found that such method if practiced as taught will result in areas on the exposed film which are not exposed or are double exposed. Therefore when viewed through a lenticular screen after developing, the film will appear to have gaps or blank spaces or double exposures, resulting in an unattractive and undesirable photograph.
A significant problem exists with respect to three dimensional cameras utilizing a movable lenticular screen in that the amount of relative movement between the lenticular screen and the film is difficult to precisely control. Should the relative movement between the lenticular screen and the film be too much or too little, the gaps or double exposures mentioned above will be obtained. Accordingly, a need exists for an arrangement to precisely control the amount of relative movement between screen and film.